CSS flexbox overflow 100% width elements

Question

On mouse over, I want to transform the position of two flex element that are sitting next to each other as per the image below

The markup is as follows

<div class="container">
  <div class="element">Normal</div>
  <div class="element">Hover</div>
</div>

I want both elements to be 100% width of the parent and the second element to overflow so I can transform X on mouse over. The problem I'm having is both elements get squeezed in to the container.

I know I can wrap the two elements in another div and give it 200% width of container. But want to know if this can be done with flexbox

Answer 1

.container {
  display: flex;
  width: 200px;
  overflow: hidden;           /* hides the flex item parked outside the container */
  cursor: pointer;
  border: 1px solid black;
}

.element {
  height: 100px;
  flex: 0 0 100%;            /* can't grow, can't shrink, fixed an 100% width */
  transition: .5s;
  min-width: 0;              /* override min-width: auto default;
                                https://stackoverflow.com/q/36247140/3597276 */
}

.container:hover > .element:first-child {
  flex-basis: 0;
}

.element:first-child { background-color: lightgreen; }
.element:last-child  { background-color: orange; }

<div class="container">
  <div class="element">Normal</div>
  <div class="element">Hover</div>
</div>

You wrote:

The problem I'm having is both elements get squeezed in to the container.

That was probably because flex items are set, by default, to flex-shrink: 1, meaning they are permitted to shrink in order to fit inside the container. In my answer flex-shrink is set to 0.